With so-called computer radiography (CR), X-ray images are recorded by the X-ray radiation passing through an object, for example a patient, being stored in a so-called storage phosphor layer as a latent image. In order to read out the stored image the storage phosphor layer is irradiated with stimulation light and thus stimulated to emit emission light. The emission light, the intensity of which corresponds to the image stored in the storage phosphor layer, is collected by a detector and converted into electric signals. The electric signals are further processed as required, and finally provided for analysis, in particular for medical/diagnostic purposes, by them being displayed on an appropriate display device, such as e.g. a monitor or printer. After the read-out of the stored image the storage phosphor layer is irradiated with erasing light in order to totally erase any remaining X-ray information, and is then available for the recording of further X-ray images.
With the processes described in U.S. Pat. No. 5,072,119 and EP 0 167 835 A1 the quantity of erasing light radiated onto the storage phosphor layer when erasing is determined by means of the maximum value of the electric signals generated by the detector when reading out the storage phosphor layer. With the apparatus known from U.S. Pat. No. 4,786,808 for different strip-shaped regions of the storage phosphor layer a maximum signal value of the electric signals generated by the detector is also respectively used in order to determine from this the quantity of erasing light respectively used when erasing the strip-shaped regions.